Zeppelins float in their tethers over the Empire State Building while humans fight with ray guns far below. Cities made of pure white porcelain soar above Niagara Falls. And of course, everyone zots to work in pneumatic tubes, after gobbling down pills for breakfast and smoking some health-improving cigars. Welcome to the future, as imagined by your great-grandparents.

There's something poignant and fascinating about yesterday's visions of tomorrow, as any retro fashionista or Mars Attacks fan can tell you. But retro futurism is a lot more than wearing Victorian goggles. Here are four ways we celebrate (and parody) the stories past generations told about the crazy world of tomorrow.

Camp and Cheese

Perhaps the most common form of retro futurism is often called "camp" or "cheese." It's a style where creators appropriate old ideas about the future for satire. Classics in this genre include Rocky Horror Picture Show, which makes fun of several 1930s horror/scifi movies, from Frankenstein to King Kong (the monster Rocky even climbs the RKO Radio tower at the end, in an homage to the iconic image audiences would have seen in 1930s movie theaters). The 1980s Flash Gordon does a campy sendup of both 30s and 50s movies, while Mars Attacks is a parody of 1950s alien invasion flicks.

In the 1960s, cultural critic Susan Sontag wrote a seminal essay about camp where she described camp, in part, as "a seriousness that fails." A movie, style, book, or design can only be campy if it tries extravagantly to be serious but is so over-the-top that it simply can't be taken seriously. Today, we often call this sensibility "cheesy," as in a movie that's "so bad it's good." Yesterday's visions of the future are perfect for camp and cheese because they're often wildly exaggerated in ways that are intensely pleasing. There's a reason why 1960s and 70s Godzilla movies are always counted among the great cheese classics. They're rife with ridiculous blinky-button labs, crazy robot tech, and unbelievably serious scientists, but most importantly they're about GIANT MONSTERS. What could be more extravagant than a nuclear dinosaur ravaging Tokyo?

Sometimes retro futurism deals with the tragedy of lost tomorrows, but camp is the comedy of crap predictions. Often a movie gets claimed as camp because it depicts a crazy future world that never came to pass, like one in 50s flick IT: The Terror Beyond Space, where 1973 witnesses two Mars missions to fight rubber monsters.

There might be a reason why what seems campy or cheesy to us is roughly generational — in the 1960s, the 30s seemed campy; in the 90s, the 70s seemed cheesy, and as new cult flick Detention reveals, in the 2010s, the 90s are being mined for their cheesy goodness. The camp sensibility is a way of thumbing our nose at our parents' generation, saying in essence, "You thought that the future would be like this, but we know better now — we laugh at your predictions!"

Anachronistas

Every generation has spawned groups of people who believe they were born long after the era where they belonged. Lacking time machines, these history buffs turn anachronism into a lifestyle, dressing in the fashions of the past or creating art that looks like something that could have been made a century (or several centuries) ago.

While these anachronistas don't always treasure historical visions of the future, it's worth noting that some of the most popular vintage styles come from time periods where people were obsessed with futuristic technologies and scientific innovation. The late nineteenth century is a popular period, as are the roaring 1920s, the "space age" 50s and the futurepocalypse-obsessed 70s.

What distinguishes anachronista style from other types of retro futurism is an earnest desire to perfectly recreate historical styles. Movies like Sky Captain and the World of Tomorrow and John Carter are good examples — these movies try to meticulously render the future as seen by the 1930s and the 1910s respectively. Though there may be jokes in these movies, there is no hint of campy satire.

Alternate History

Whole books could be written about what alternate history is, and how it works as retro futurism. There are alternate history stories that are clearly parodies, like the forthcoming Nazis-in-space movie Iron Sky; and there are deadly serious ones like William Gibson and Bruce Sterling's The Difference Engine (where computers are invented in the nineteenth century) or Philip K. Dick's classic mind-bender The Man in the High Castle (where a guy in Nazi-occupied America is obsessed with an alternate history novel about what would have happened if the Allies had won the war).

Often an alternate history can reveal how retrograde our current visions of the future really are. You can see hints of this in Scott Westerfeld's Leviathan saga, where World War I is being fought using genetically-engineered creatures and robots. Here, Westerfeld has taken today's vision of the future, full of GMOs and cyborgs, and plunked it neatly into what is often considered the last pre-modern war.

Other retro futurist alternate histories feel like wish fulfillments about the present day. Imagine how much more advanced our technology would be right now if we'd actually had computers in the 1880s! Or if we'd gone to Mars in the 1910s!

Regardless of whether alternate history promises to make today's future more like history, or convert history into our vision of the future, it's one of the most potent genres for re-imagining tomorrow by reaching into the past.

Ye Olde Punk

No discussion of retro futurism would be complete without a nod to the wild and unexpected popularity of steampunk, dieselpunk, clockpunk, and every other genre or fashion that converts historical visions of the future into contemporary style. Steampunk is often an amalgam of anachronista style, camp, and alternate history, and its fans generally mine history looking for futuristic trends and ideas. The "punk" aspect of all this can be interpreted in a number of ways. But for the purposes of retro futurism, it means a fascination with disruptive periods in history, and with the people in history who questioned mainstream ideas about right and wrong.

I'm picking on steampunk here, but there are plenty of other historical periods that have been turned into punk — and these are almost all periods where the public was actively engaged in a discussion about what it would be like to live in a future utterly transformed by science and technology. There's a reason why nobody does medieval punk (except the anachronistas in the SCA). Punking history only becomes fun when we reach the age of clocks, the sixteenth century, when suddenly new technologies of ocean travel and mechanization made it obvious that the future would look really different from the present.

So why do we look to the past for our visions of the future? Sometimes it's to laugh, and sometimes it's to mourn the golden tomorrows that never came to pass. But often, when we look to the future, we want a sense of connection with all those people before us who also looked forward to tomorrow. The failures of history, after all, are what teach us to dream the future better.